FAA Aviation Safety
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General Aviation
Joint Steering Committee
Safety Enhancement Topic
Avoiding Adverse Drug Interactions Impairment from medication, particularly over the counter (OTC) medication, has been cited in a number of accidents in general aviation. In a 2011 study from the FAA’s CAMI Toxicology Lab, drugs/
medications were found in 570 pilots (42%) from 1,353 total fatal pilots tested. Most of the pilots with
positive drug results, 90%, were flying under CFR Part 91.
What’s the Problem?
We all know that some drugs may
compromise a pilot’s ability to control the aircraft
and/or adversely affect judgment and decision
making. The difficulty comes for accident
investigators in trying to quantify the known
detriment that comes with various medications and
the underlying conditions that require their use.
Another area of concern is that airmen do
not always disclose all of their medical conditions to
their Aviation Medical Examiner (AME). Both the
undisclosed condition and the treatment can
endanger the airman and compromise public safety.
Undisclosed treatments could hide potentially
impairing drug interactions. That’s why it’s
important to disclose any medications you are
taking to your AME. According to a 2015 CDC study,
nearly 74% of doctor office visits resulted in drug
therapy and 24% of the U.S. population had 3 or
more prescriptions. In addition, many medications
have unexpected interactions with other
medications, including over the counter medications
(OTCs), supplements, and herbals. For example,
antihistamines can adversely react with some
prescription drugs used to treat high blood pressure.
These interactions can be exacerbated in the aviation
environment.
Also certain foods can increase or decrease the
concentration of some drugs. An example is grapefruit or
grapefruit juice which can affect how long some
medicines may stay in the body and may cause
dangerous side effects. Here’s a resource you can use to
learn more about adverse food and drug reactions:
https://bit.ly/3jvOCZF. It describes some but by no
means all, adverse drug and food interactions.
How Long?
So if you have to take an impairing medicine,
how long should you wait before you resume flying?
Every medicine is different, but a good rule of thumb is 5
times the half life of the medication, or by the dosing
interval (if the half-life information is unavailable). If a
medication says to take it 4 times per day, the dosing
interval would be 6 hours. Therefore the wait time after
the last dose would be 30 hours (6 hours x 5 = 30 hours).
Other medications may have longer or shorter intervals
which is why it’s important to talk to your AME.
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Where Can I Get More Information?
A good place to start is the new OTC
medication guide listed below. The guide provides
pilots with a list of OTC medications that are used to
treat a common ailment that are generally safe
(GO) and those that are not (NO-GO). Take a close
look at this list because some medications we
regard as equivalent may have very different
impacts on safety. Be sure to check out the Do Not
Issue/Do Not Fly section too. You can also find good
information on drugs through trusted government
sites like the National Institute of Health’s Medline
site at https://medlineplus.gov. This site lists both
generic and trade names along with side effects and
warnings for almost every drug out there.
What to Look For
The Food and Drug Administration (FDA)
requires standard labeling for all OTC medications.
These standard medication labels include the active
ingredients, directions for use, and highlight
potential side effects like drowsiness in the warning
section. Be sure to check out our new OTC
medication guide listed on the right.
Supplements may also interact with OTC
and prescription medications to cause impairment.
It’s also important to note that supplements may
have similar labels, but are not regulated by the
FDA, and therefore do not need to meet a specific
standard. This is especially true for cannanbidiol
(CBD) products. The CBD industry has widely varying
quality control and labeling leading to significant
discrepancies from package labels including much
higher THC levels than disclosed. This can cause
both impairment and possibly a positive drug test.
Therefore, the FAA recommends against the use of
CBD products by airmen.
Resources
What OTC Medications Can I Take and Still Be
Safe To Fly?
www.faa.gov/go/pilotmeds
AME Guide — Pharmaceuticals
www.faa.gov/about/office_org/
headquarters_offices/avs/aam/ame/guide/pharm/
AME Guide — Do Not Issue — Do Not Fly
www.faa.gov/about/office_org/
headquarters_offices/avs/offices/aam/ame/guide/
pharm/dni_dnf/
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